Transcript No Slide Title

The Effect of High Concentrations of GA3 and Seed Age
on Germination of Silene latifolia
Allison Amore, Meredith Harry, William Wood
Department of Biology, Davidson College
Age Decreases Viability
Question
1
0.95
Do increased concentrations of GA3 and/or seed age affect germination in Silene latifolia?
Mean

2002
2003
0.9
0.85
Background
0.8
H20
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


White campion, (Silene latifolia or Silene alba) - dioecious, perennial plant, native to Europe
- excellent model species to study the dynamics of a fragmented plant populations (McCauley,
1994)
Builds and maintains seed banks (Peroni and Armstrong, 2001)
Researchers need effective way to break seed dormancy
GA3 – naturally occurring plant hormone
- promotes intake of cell wall hydrolases and weakens thick cell
layers of endosperm
- allows radicle to emerge from the seed coat (Leubner, 2003)
Previous study indicates increasing GA3 concentration increases mean fraction germination (Bio
341, Spring 2002, unpublished data)
GA3 Increases Germination of Viable Seeds


0.93
2002
2003
0.83
0.73
H20
Low
Med
High
Treatment
Fig 4. Mean germination of viable seeds. Error bars = 1se; N=5 reps/GA3 treat/year
with 50 seeds per rep
1000 seeds obtained from 2002 and 2003 seed crops from same population
Groups of 50 seeds randomly assigned to treatment in Petri dish
- 5 replicates of each treatment (Table 1)
Petri dish – 60 mm with filter paper saturated with appropriate treatment (Fig 1)
Placed in re-sealable plastic bags in growth chamber
- 14 hr light, 10 hr dark at 22°C
Censused daily for 14 d
- germinated seeds removed (1 mm of radicle extended)
After 14 days ungerminated seeds tested with tetrazolium for viability (Cottrell, 1947)
Treatment
Concentration of GA3
Control
Distilled water
Low
2.601 X 10-3 M
Medium
1.170 X 10-2 M
High
2.601 X 10-2 M
Table 1. Description of treatments.
Conclusions
Results
GA3 Increases Germination

GA3 increases mean fraction germination of seeds independent of seed age or concentration
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Seeds from 2002 germinated at a higher mean fraction while seeds from 2003 had a higher mean
viability

GA3 overcame the after-ripening requirement for the 2003 seeds
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A GA3 concentration of 2.601 X 10-2 M showed no toxicity
Future Research
1
0.9
Mean


High
Fig 3. Mean seeds viable. Error bars = 1se; N=5 reps/GA3 treat/year with 50 seeds
per rep
Methods
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
Med
Treatment
Mean

Low
2002
2003
0.8
0.7
0.6
H20
Low
Med
High

Test higher concentrations of GA3 to determine toxicity level
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Test a population using more years with a greater gap between them

Test other populations of white campion
Treatment
Fig 1. 60mm Petri dish with 50 seeds on
saturated filter paper
Fig 2. Mean fraction germination of all seeds. Error
bars = 1se; N=5 reps/GA3 treat/yr with 50 seeds per
rep
Acknowledgements
We would like to thank Dr. Patricia Peroni for her valuable assistance and the
previous Bio 341 lab group.